Veterinary 2025 Guide: Lomustine (CCNU) Chemotherapy in Dogs & Cats 🐶🐱🩺

I’m Dr Duncan Houston BVSc. This comprehensive 2025 guide explains the safe and effective use of lomustine (CCNU)—an oral alkylating chemotherapy commonly used in veterinary oncology. We'll cover indications, dosing, adverse effects, handling protocols, monitoring, and patient support tools 😊.

🔎 1. What Is Lomustine?

Lomustine (brand names Gleostine®, CeeNU®) is a nitrosourea alkylating agent with high oral bioavailability (~100%) that penetrates the blood–brain barrier—ideal for brain tumors as well as lymphomas and mast cell tumors :contentReference[oaicite:3]{index=3}.

🎯 2. Clinical Uses

• Rescue therapy for relapsed lymphoma in dogs and cats; up to 25–50% achieve partial or complete remission :contentReference[oaicite:4]{index=4}.
• First-line for cutaneous lymphoma—80–90% response rate, 26% complete remission :contentReference[oaicite:5]{index=5}.
• Effective for mast cell tumors, brain/spinal cord tumors, melanoma, and select sarcomas :contentReference[oaicite:6]{index=6}.

💊 3. Dosing & Administration

• Oral capsule, given with food; avoid antacids and food for 2 hours post-dose to reduce GI upset :contentReference[oaicite:7]{index=7}.
• Typical dose: 50–90 mg/m² every 3–8 weeks—schedule tailored to cancer type and patient tolerance :contentReference[oaicite:8]{index=8}.
• Metronomic approach (lower, more frequent doses) may decrease angiogenesis with fewer side effects :contentReference[oaicite:9]{index=9}.

⚠️ 4. Handling & Safety

Lomustine is a hazardous drug. Use gloves when handling, administering, or disposing of waste (urine, feces, vomit, blood)—double-bag as per guidelines—especially critical for pregnant or immunocompromised individuals :contentReference[oaicite:10]{index=10}.

🧬 5. Main Adverse Effects

• Myelosuppression: delayed neutropenia around 4–6 weeks—CBC should be done 1 week post-dose and before next treatment :contentReference[oaicite:11]{index=11}.
• Gastrointestinal signs: anorexia, vomiting, diarrhea—treated with anti-emetics (maropitant, ondansetron) :contentReference[oaicite:12]{index=12}.
• Hepatotoxicity: jaundice, elevated liver enzymes, lethargy :contentReference[oaicite:13]{index=13}.
• Pulmonary toxicity: fibrotic changes possible with chronic use :contentReference[oaicite:14]{index=14}.
• Delayed toxicity: cumulative dosing may cause bone marrow, liver, kidney dysfunction, secondary malignancy :contentReference[oaicite:15]{index=15}.

🩺 6. Monitoring Protocols

• Baseline CBC and chem panel (liver, kidney, pulmonary assessment) prior to initiation.
• CBC 7 days post-dose to detect neutropenia; repeat before next dose.
• Reassess every 3–4 weeks, including physical exam, weight, appetite, and side effects.
• Imaging or restaging as indicated based on tumor type and therapeutic goals.

🤝 7. Supportive Care Recommendations

• Prophylactic anti-emetics for GI upset.
• Hospitalize febrile or neutropenic patients; consider antibiotics.
• Provide appetite stimulants, nutritional support, and hydration.
• Adjust dosing schedule or dose based on adverse effects or CBC results.
• Consider metronomic dosing for better tolerance in fragile pets.

📣 8. Client Communication & Home Care

• Explain treatment timeline, expected onset of effects (~weeks), and side effect window (4–6 weeks post-dose).
• Demonstrate safe handling, waste disposal, and glove use.
• Use Ask A Vet app for appointments, reminders, side-effect logging, and vet contact.
• Educate on when to contact vet (fever, vomiting, diarrhea, bleeding, lethargy).

📋 9. 2025 Vet Takeaways

• Lomustine is a lipophilic, orally bioavailable chemotherapy ideal for hard-to-reach tumors.
• Highly effective as rescue therapy for lymphoma and cutaneous mast cell tumors.
• Requires cautious dosing, scheduled CBC monitoring, and vigilant supportive care.
• Handle as a hazardous drug with strict safety protocols.
• Monitor long-term toxicity risks—myelosuppression, hepatotoxicity, pulmonary damage, secondary cancers.
• Utilize client tools like Ask A Vet to enhance compliance and safety 😊.

At Ask A Vet, we equip you with treatment trackers, dosing timers, side‑effect logs, and emergency vet access to support lomustine therapy. Download our app to enhance oncology patient care and owner confidence ❤️